1. Field of the Invention
The present invention relates to a method and device for measuring fluctuations in the cross sectional area of a bundle of hair for the purpose of documenting the clinical course of medical hair loss disorders and the effectiveness of hair growth treatments and/or for the purpose of indirectly calculating the severity of balding disorders or efficacy of hair growth treatment as evidenced by a decrease or increase in hair population and/or hair shaft diameter.
2. Description of the Related Art
Heretofore, a hair volume-measuring device used for measure of hair damage was disclosed in the Kabacoff et al. U.S. Pat. No. 4,665,741.
Hair shedding is a condition characterized by loss of hairs of normal-sized diameters. It is one of the two major categories of hair loss. Shedding is diffusely distributed over the scalp and may be the sign of several medical abnormalities and toxicities. It may physiologically follow high fever, cessation of birth control pills, or childbirth. Shedding is characterized by the appearance of skin on the scalp where hair was once present. Shedding may be quantified by measuring the density of hairs present in an area of one-centimeter square of scalp. Hair density usually is measured by closely cutting the scalp hair (about 2 mm long in an area 5 mm×5 mm) and then counting the remaining cut hairs present on the scalp and multiplying that value times 4. The hair density of normal individuals in the absence of shedding ranges between 120 to 200 hairs per sq cm of scalp.
Hair thinning is a condition characterized by the gradual miniaturization of individual scalp hairs. It is the second major category of hair loss. The appearance of hair loss is the result of decreasing diameters resulting in the eventual absence of hairs. Thinning (like shedding) also is characterized by the appearance of skin on the scalp where hair was once present. Thinning affects an estimated 75% of men and 10% of women. Unlike shedding, it is not diffuse in its distribution over the entire scalp surface, but almost always appears in a pattern, with hair loss on the top of the scalp. Thinning characteristically spares the posterior and sides of the lower scalp, creating a familiar horse-shaped fringe that persists in spite of the most advanced cases.
Thinning occurs in healthy individuals and is referred to as balding, pattern balding, male or female pattern alopecia, androgenctic alopecia, male or female pattern balding. It is considered normal in 75% of men. And, although it may occur in healthy women, it may indicate an endocrine abnormality in a small group of women.
Early pattern balding is difficult to recognize and difficult to quantify. Simple density measurements (as performed in shedding) are of little value because there is a mixed population of both normal-sized and miniaturized hairs. When density counts are performed, a normal and miniaturized hair would each be counted as one hair. Therefore, in order to detect and quantify thinning in a meaningful manner, the actual hair mass (the collective cross sections of hair from a pre-determined area of scalp) must be measured. This alone would reflect the density of hairs and the array of mixed diameters that are present.
In order to quantify pattern and diffuse hair loss, scientists have commonly used three basic methods:                1. Hair density count        2. Clinical photography        3. Hair weight.        
Quantification of hair loss by measuring the collective cross sections in a pre-determined area of scalp has not been reported in the scientific literature nor disclosed in prior U.S. patents.
The three commonly used methods are described in more detail below:
Density count: The density of an area of scalp is compared to the known normal range of values, which is 120 to 200 hairs per sq cm. To determine the percent loss of density for a single individual, the density on the top part of the scalp (the area of loss) may be compared to the density on the lower back and sides (the normal and permanent hair zone). The percent hair loss is calculated by dividing the hair count in the hair loss area by the hair count in the permanent zone. This method is quite imprecise in conditions of thinning, because it measures only the number of hairs and makes no allowance for their variations in diameter. The method is used however because it is a bit more precise than clinical photography. It requires cutting off hair and direct scalp exam with a hand lens or video microscope.
Clinical photography: Photography is performed comparing the patient's hair loss area to the permanent zone. It may also compare the patient's hair loss zone to a picture of the same zone of a patient with no hair loss, or of a prior or subsequent state of loss in the same patient. In this manner, the growth or loss is grossly quantified by visual observation alone. No insight is gained into whether or not the hair loss is the result of thinning or shedding. Photography is quite imprecise and obscured by various hairstyles and hair lengths. It is however the most common form of hair loss documentation because it is rapid, requires not special training and is easily archived. It does not require the cutting of hair, but does require standard photo equipment lighting, positioning of hair, and standardized hair length, to yield any kind of comparable data.
Hair weight: A small area of hair (usually 5 mm×5 mm) is shaved from a balding area. The patient returns in 30 days and the newly grown hair is cut and weighed. The value is compared to a subsequent similar assay of the same area. In cases of pattern loss, the procedure may be performed in the permanent zone (lower posterior and lateral horseshoe shaped zone) and compared to the value in the thinning zone. The percent hair loss may be calculated by dividing the hair weight in the thinning area by the hair weight in the permanent zone. Hair weight is a very precise method of measuring hair loss because it considers both the number of hairs and their diameters and the hair length in its calculation. Its disadvantage is that the sample size represents a relatively small sample of the scalp surface, and because it measures hair length as well, it may not be as meaningful as thought.
Furthermore it is a very tedious process and impractical to perform in a clinical setting. It also requires cutting off hair. It is used primarily by commercial laboratories to measure the effectiveness of hair-growing preparations i.e. finasteride, dutasteride, and minoxidil.